Mandrel for tube rolling mills



April 16, 1935. A. P. DlEscHER 1,997,997

I MANDREL FOR TUBE ROLLING MILLS Filed March 5, 1933 s sheets-sheet 1*zz zo z3 FIG 2.

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MANDREL FOR TUBE ROLLING MILLS Filed March 5, 1933 5 Sheets-Sheet 2 l@kz FI G. 4 za I @www Mmmffm A TTOF/VEY April 16, 1935.

A. P. DIESCHER MANDREL FOR TUBE ROLLING MILLS Filed March 5, 1933 3Sheets-Sheet 5 Sw NM wh R. bv Q .5 @www Patented pr. 16, 1935 REL FRTUBE RELING MILLS August P. Biescher, Pittsburgh, Pa., assigner toDiescher Tube Mills,

lino., Pittsburgh, Pa., a

it) Claims.

My invention relates to apparatus for treating tubular blanks, andparticularly to mandrels for use in treating tubes of relatively largediameters by means of cross-rolling.

In reducing the wall thickness and increasing the length of tubes in across-rolling mill, it is advisable to employ a mandrel the outsidediameter of which is smaller than the inside diameter of the finishedtube. When the tubes are of relatively large internal diameter it willbe appreciated that the weight of a solid mandrel of the necessarydiameter may be such as to damage lthe relatively thin walls of acompleted tube which encloses it when they are delivered from. thecrossrolls.

A hollow mandrel of sufficient wall thickness to resist the forcesexerted by the cross-rolls upon the tubular blank would be lighter thana solid mandrel, but its weight would still be excessive in connectionwith the handling of the completed large tube with the mandrel in theinterior thereof.

In accordance with the present invention, I provide a relatively lighttube, orv cylindrical shell, the wall thickness of which is ysufilcientto withstand all of the stresses to which an elongator mandrel maynormally be subjected in handling but is not sucient to withstand theforces of cross-rolling vthat tend to crush the mandrel during theelongation of a tubular blank; and I provide in the interior of thehollow shell a reinforcing plug which may rotate with the hollow shellbut is retained in its longitudinal position between the cross-rolls forreceiving the forces of the latter as the tubular blank and the hollowshell pass therethrough. y

The hollow cylindrical shell may therefore ad- Y vance through the rollsand rotate with the tubular blank during its elongation,'while thereinforcing plug in the interior thereof remains in its longitudinalposition but may rotate with the shell. By means of this arrangement, Iam enabled to provide a mandrel member to move with the tube ofsuiiiciently light construction to be easily handled and to avoiddamaging, by reason of its Weight, the highly heated thin walls of tubesof large diameter as they emerge from the crossrolls.

The details of my invention will be described in connection with theaccompanying drawings, in which,

Figure l is a plan view of a portion of an elongator in operation upon atubular blank having a mandrel constructed in accordance with my in-(ei. rsu-its) vention, the blank and mandrel being in horizontal sectionand parts being broken away.

Fig. 2 is an enlarged longitudinal sectional view oi a portion of themandrel of Fig. l.

Figs. 3 and 4 are views similar respectively to Figs. 1 and 2 of amodification.

Fig. 5 is a longitudinal sectional view of a portio of a mandrel offurther modied construction.

Fig. 6 is a ytransverse sectional view taken on line VI-VI oi Fig. 5.

Fig. 7 is a similar view on line "VE-VII of Fig. 5. Fig. 8` is a frontend elevation of the mandrel of Fig. 5.

mandrel 4 therein.

The mandrel l comprises a relatively light cylindrical shell 5 that isprovided Witha conical head 6 which is screw-threaded into an end piecel and fastened therein by Ymeans of a suitable rivet 8. The end piece lis secured to the shell 5 by means of the rivet B and rivets 9.

A reinforcing plug il! is located in the interior of the shell 5 for thepurpose of resisting the crushing forces exerted by the cross-rolls uponthe tubular blank 3 and shell 5 as they pass through the elongator. Theplug I vcomprises a hollow cylindrical member l and secured to theforward l having tapered ends end of a tubular rod i2 which retains theassembly of the plug Il) in its illustrated longitudinal position,

The member i i has a close or running t with the interior of the shelland may rotate with the latter. The rod l2 may be secured at itsleft-hand end, not shown, by any suitable vmeans such, for example, as athrust bearing which will restrain the rod l2 and the plug IllV fromlongitudinal movement to the right as viewed in Fig.- 1, but which willpermit the rotation of these parts with the shell 5.

The hollow member Il is mounted, upon a reduced portion of the rod l2and is suitably keyed thereto by a key- I3. The member Il is securedupon the rod l2 by means of a bushing nut I4 screw-threaded on theforward end of the rod I2 and prevented from rotation by a suitablerivet l5. The interior of the tubul ar rod l2 is provided with a tube I6that is spaced from the interior wall of the rod i2 and is secured tothe forward end of the latter by means of interior screwthreadedbushings l1 and I8. The tube I6 serves as an inlet for water for coolingthe interiorl of the conical head 6 and of the hollow shell 5 of themandrel 4 andthe walls of the tapered member Il. The space around thetube I6 within the tubular rod I2 affords a. passage having an outletthrough a radial tube I9 for a suitable lubricant for the interiorsurface of the shell 5 whereby the latter may move over the reinforcingplug I0 without undue friction therebetween which might otherwise becaused by the pressure exerted upon the plug I0 by the shell 5 becauseof the forces exerted by the cross-rolls I and 2.

In the operation of an elongator employing my improved mandrel, atubular blank is provided with a hollow shell 5 and a plug I0 isinserted within the shell 5 against the mandrel head 6 at any suitablepoint in the travel of the blank and mandrel to the cross-rolls. It ispreferable that the thrust block or other device for retaining the rodI2 and the connected plug I0 in their longitudinal positions be soarranged that it may advance with the plug iii and the shell 5 andtubular blank 3 until the plug I0 is in its working position between thecross-rolls as illustrated in Fig. 1.

When the tubular blank 3 enters the cross-rolls it is drawnlongitudinally therethrough and rapidly rotated and the mandrel shell 5which is closely engaged by the tubular blank 3 moves in the samedirectionv as the latter, but not necessarily at the same rate. The plugIIJ, however, re-

mains in position between the cross-rolls in the zone in which forcesare exerted by the crossrolls in reducing the Wall thickness of theblank 3 upon the mandrel 4. It will be appreciated that no wall-reducingforces are exerted upon the portion of the completed tube that haspassed through the cross-rolls and is beyondthe plug I0.

During the cross-rolling operation water is supplied through the tube I6and it flows intothe forward portion of the shell 5 beyond the plug. Itis desirable that the water be supplied under such pressure and at suchrate that itsvolume beyond the plug will increase more rapidly than thespace beyond Vthe plug I0 in order that it will be under pressure toinsure a satisfactory rapid return flow.

The cooling water returns along the shell 5 and through a series ofinclined openings 20 in the wall of the hollow member II to cool thelatter. This cooling effect is increased by the rotation of the plug I0since any water entering the openings 20 in the forward end of the plugwill flow around at least a portion. of the interior of the hollowmember II before it flows out through the p openings 29 at the rear ofthe member II. The returning cooling water continues to the trailing endof the mandrel shell, whereupon it may be either cooled and recirculatedor disposed of in any suitable manner.

In case such operation appears desirable, the direction of flow ofcooling water may be reversed, the ,water being supplied through theshell 5 surrounding the tube I2. This arrangement insures an adequatesupply of cooling water to the plug I0 at all times since it flowsthrough .the openings 20 before passing to the forward end of themandrel. Water will not return until it reaches a level in the forwardend of the mandrel that permits it to flow into the forward end of thetube I6.

The cross-rolling operation continues until the entire blank 3 haspassed through the cross-rolls to the delivery side of the elongator.

If the elongating apparatus is of the type in which the mandrel isreturned to its starting point by passing around the elongator in themanner described, for example, in my copending application Serial No.602,145, led March 31, 1932, it will be necessary that the plug I8 beWithdrawn after the elongation of each tube and for such distance fromthe cross-rolls on the entry side thereof as will permit a fresh mandrelshell to be placed into position to enter the crossrolls. The plug maythen be advanced into the forward end of the fresh mandrel shell at anysuitable time before the tubular blank enters the cross-rolls. All ofthese parts are then advanced into the cross-rolls.

In the event that the elongating apparatus is of the type wherein themandrel is stripped from the completed tube by drawing it back throughthe cross-rolls after each elongation, the plug I0 must be withdrawnalong with the mandrel shell for such distance as is suiiicient topermit the next tubular blank or billet to be disposed in the elongatorinlet between the mandrel head or point and the elongator. Inwithdrawing the mandrel shell in this manner the plug Il) willnecessarily be carried with it after the mandrel head has engaged theforward end of the rod I2 to the forward end of which is connected tothe stem 22 by means of a washer 25 and an internal bushing 26.

A tapered nozzle 21 has a screw-threaded connection to the interior ofthe hollow stem 22 and is in alignment with the pipe 24. Between thebushing 26 and the rearward end of the nozzle 21 is a series of radialopenings 28 that extend through the stem 22 and communicate with thehollow interior of the tapered member II. lIfhe nozzle is also providedwith radial openings 29 adjacent its screw-threaded connection to thestem 22.

In the operation of this form of my invention,

water is supplied through the pipe 24 and it is forced forwardly throughthe nozzle 21 toward the forward end of the mandrel. In addition acertain amount of water flows radially through the radial openings 28for the purpose of cooling the interior of the member II. Water alsoflows radially through the openings 28, this portion of the waterflowing at the forward end of the stem 22 into the shell adjacent theforward end of the hollow member I I.

It is possible that during the operation of the cross-rolls the mandrelshell 5 may advance with the tubular blank 3 at such rate as compared tothe rate of water supply that the water does not ll the rapidlyincreasing space in front of the member II. In such case water from thespace in front of the memberll will not flow back through the front andrear openings' 20 of the member I I. It is important therefore in suchcase that means such as the radial openings 28 be provided in order toinsure that a certain portion of the cooling water flows into theinterior of the member I l. The nozzle 21 provides suflicient4 backpressure to the iiow of water through the pipe 24 that water will fiowradially through the openings 28 and also through the openings 29 forthe purposes described above.

In case the forward end of the mandrel is not lled by the cooling water,the nozzle 21 will operate to so increase the velocity of the water thatit will be thrown a considerably greater distance toward vthe forwardend of the mandrel than 'would be the case if the water owed through apipe of uniform bore.

Reference may now be had to Figs. 5, 6, 7 and 8 in which is illustrateda further modification. As in the form of my invention shown in Figs. 3and 4, the member II is provided with a central stem 30 to which isconnected a tubular rod 23. A pipe 24 is connected to the stern 30 inthe manner de scribed in connection with the apparatus of Figs. 3 and 4.

The forward end of the stern 30 is provided with a bushing 3| throughwhich projects a pipe 32 that is rigidly connected to a bushing 33 inthe head of the mandrel. The pipe 32, which is provided with a series ofradial openings 34 adjacent the head of the mandrel, has a loosetelescoping iit with the pipe 24, these parts overlapping to such extentas to permit the movement of the mandrel shell during the operation ofcross-rolling a tube without the tube 32 being completely withdrawn fromthe pipe 24.

'I'he mandrel head comprises a tubular bushing 36 that is secured to theforward end of the shell 5 by means of rivets 31 and an approximatelyconical nose portion 38 is screw-threaded to the bushing 33, the latterhaving a similar connection to the tubular bushing 36. As shown in Fig.8 the nose portion 38 is provided with two recesses 39 whereby the nose38 may be removed from or replaced upon the bushing 33. A screw 40 locksthe nose 38 in its illustrated position.

In the operation of the latter form of my invention, water is suppliedthrough the pipe 24 in the direction of the arrow in Fig. 5, waterflowing into the pipe 32 and being discharged therefrom through theopenings 34 at the forward end of the mandrel. Water also traverses theannular space between the pipe 24 and the pipe 32 and enters the annularspace within the stem 30. The latter is provided with radial openings 4Ithrough which water is forced into the interior of the hollow taperedmember Il..

Water also iiows through the relatively small annular opening in thebushing 3l surrounding the pipe 32 and is discharged into the shell 5adjacent the forward end of the member I I. 'I'he reiurn fiow of thecooling water is through the inclined openings 20 as in the other formsof my invention. If the rate of increase in the volume of the spacewithin the mandrel shell in front of the member I I is faster than therate at which water is supplied thereto. there may be liitle or noreturn flow through the openings 20 from such space. In such case,however, the arrangement whereby the water is transmitted to threeportions of the mandrel insures that all of the essential parts of thelatter will be cooled regardless of the relation of the rate of increasein space to that of the supply of Water. The openings 34 insure that theforward end of the mandrel will be cooled, and the openings 4I insurethat water will be supplied to the interior of the member Il. The waterflowing through the annular opening in the bushing 3| insures that somewater will be directed to a portion of the shell adjacent the member II.

Mandrels constructed in variousforms in accordance with my inventionpermit the crossrolling of a tube of relatively large diameter upon amandrel of such weight that it is easily handled and that the highlyheated thin walls of the tube will not be damaged when the tube and themandrel shell therein emerge from the cross-rolls. At the same time thestrength of the mandrel shell reinforced by the plug contained thereinis suiiicient to resist the crushing forces of the cross-rolls and tothereby insure that the elongation of the tubular blank will occur withthe same efficiency and satisfactoryresults that would be secured ifsolid mandrels were employed.

'Ihe foregoing and other advantages will be apparent to those skilled inthe art of construc-v out the latters annular extent as the shellprogresses forwardly over the plug.

2. A mandrel adapted for use in a tube rolling mill, comprising a rodanchored at its outer end for rotation on its axis and againstlongitudinal movement, a plug having a cylindrical outer face attachedto said rod and adapted to be held thereby in the working pass of amill, and a long cylindrical blank-supporting shell slidably mounted forlongitudinal movement upon said plug which is formed to reinforce saidshell throughout the latters annular extent as the shell progressesforwardly over the plug.

3. A mandrel adapted for use in a tube rolling mill, comprising a rodheld against longitudinal movement, a plug having a cylindrical outerface attached to said rod and adapted to be held thereby in the Workingpass of a mill, and a long cylindrical blank-supporting shell slidablymounted for longitudinal movement upon said plug and provided at itsforward end with a tapered head for entering the shell into a tubularblank, said plug being formed to reinforce said shell throughout thelatters annular extent as the shell progresses forwardly over the plug.

4, A mandrel adapted foruse in a tube rolling mill, comprising a rodheld against longitudinal movement, a plug having a cylindrical outerface attached to said rod and adapted to be held thereby in the workingpass of a mill, and av long cylindrical blank-supporting shell slidablymounted for longitudinal movement upon said plug and having its forwardend closed by a tapered head for entering the shell into a tubular blanksaid plug being formed to reinforce said shell throughout the lattersannular extent as the shell moves forwardly over the plug.

5. A mandrel adapted for use in a tube rolling mill, comprising a,tubular rod anchored at its outer end against longitudinal movement, aplug having a cylindrical outer face attached to said rod and adapted tobe held thereby in the working pass of a mill, a long cylindricalblank-supporting shell slidably mounted for longitudinal movement uponsaid plug and having its forward end closed, said plug being formed toreinforce said shell as the latter moves forwardly over the plugandpbeing provided with openings for the flow of cooling fluid t-hroughit and through said tubular rod.

6. A mandrel adapted for use in a tube rolling mill, comprising atubular rod anchored at its outer end for rotation on its axis andagainst longitudinal movement, a plug having `a cylindrical outer faceattached to said rod and adapted to be held thereby in the working passof a mill, and a long cylindrical blank-supporting shell slidablymounted for longitudinal movement upon said plug and provided with anend-closing head which is tapered for entering the shell into a tubularblank, said plug being 'formedto re- I inforce said shell as the lattermoves forwardly over the plug and being provided with openings for theow of a cooling fluid through it and through said tubular rod and to theclosed end of said shell.

'1. Av mandrel for use in a. tube rolling mill, comprising a longcylindrical shell adapted to advance longitudinally within a tubularblank during passage of the blank through the mill, a reinforcing plugWithin said shell having a cylindrical outer face, and a rod extendingwithin the shell and held at its outer end against longitudinalmovement, said plug being attached to said rod and held thereby againstlongitudinal movement positioned in the working pass of the mill whilethe shell advances longitudinally.

8. A mandrel for use in a tube cross-rolling mill, comprising a longcylindrical shell adapted to rotate and advance longitudinally within atubular blank during passage of the blank through the mill, areinforcing plug within said shell having a cylindrical outer race, anda rodV extending within the shell and held at its outer end againstlongitudinal movement, said plug being attached to said rod and heldthereby against longitudinal movement positioned in the working pass ofthe mill while the shell advances longitudinally, said plug being freeto rotate with said shell.

9. A mandrel for use in a tube cross-rolling mill, comprising a longcylindrical shell adapted to rotate and advance longitudinally within atubular blank during passage of the blank through the mill, areinforcing plug within. said shell having a cylindrical outer face, anda rod extending within the shell and held at its outer end againstlongitudinal movement but free to rotate, said plug being attached tosaid rod and held thereby against longitudinal movement positioned inthe working pass' of the mill while the shell advances longitudinally.

10. A mandrel for use in a tube rolling mill. comprising a longcylindrical shell adapted to advance longitudinally within a tubularblank during passage of the blank through the mill, a reinforcing plugwithin said shell having a cylindrical outer face, and a rod extendingwithin the shell and held at its outer end against longitudinalmovement, said plug being attached to said rod and held thereby againstlongitudinal movement positioned in the working pass of the mill whilethe shell advances longitudinally, and said rod and plug being providedwith a passageway for supplying lubricant to the exterior of the plug.

AUGUST P. DIESCHER.

